New multiblock copolymers of norbornene and 5-hydroxycyclooctene

Synthesis of bis-(benzocyclohexan-ketoimino) Ni(ii) with different electron groups and their catalytic copolymerization of norbornene and polar norbornene

“…Norbornene (NB) and its derivatives are polymerizable owing to the existence of ring strain, thus norbornene has become one of the most active participants in cyclo-olen copolymerization. 3,4 Vinyl-type polynorbornene (PNB) does not contain any double bonds and with a rotationally strongly constrained conguration, 5 which consists of rigid alicyclic polymer backbone, it features many advantageous qualities, such as high thermal stability, high glass transition temperatures (T g ), high optical transparency, large refractive index, low birefringence, low dielectric constant, low moisture absorption as well as low cost. These advantages have been widely applied in many microelectronic and optical applications.…”

Olefin metathesis in multiblock copolymer synthesis

“…The substantial difference in the monomer strain energy (NB: 100 kJ mol −1 , − Δ G° ROMP = 47 kJ mol −1 ; COE: 16 kJ mol −1 , − Δ G° ROMP = 13 kJ mol −1 ) [77,96] is the reason for such behavior. Unlike copolymerization, the MCM starts from two homopolymers, PNB and PCOE, in which there is no difference in the strain energy, so that multiblock copolymers with various block lengths are easily formed [88–89 91,93]. Obtaining of multiblock polymers using cross metathesis is synthetically much simpler than using the earlier described sequential ROMP or pre-synthesized block-coupling techniques so that MCM can be advantageous when a strict sequence control over the copolymer structure is not needed.…”

“…Cross metathesis in the PNB/PCOE (Fig. 6) and PBD/PI pairs was monitored by 13 C NMR [87–91 93]. The fraction of heterodyads in the copolymer gradually increased with conversion thus indicating the formation of random multiblocks.…”

“…We introduced substituents into NB–COE copolymers by premodification of NB blocks or COE blocks (Fig. 4) [91,93]. A bulky Me 3 Si-substituent that can enhance gas separation properties was introduced into NB copolymer blocks by the cross metathesis of poly(5-trimethylsilylnorbornene) with PCOE [89].…”

“…Kinetic studies demonstrated that a substituent in the NB monomer units considerably lowers the MCM rate. The introduction of hydroxy groups into COE units of a NB–COE copolymer met certain difficulties mainly related to the poor solubility of the parent poly(5-hydroxycyclooct-2-ene), PCOE(OH), homopolymer in common solvents [91,97]. The cross metathesis of PNB with PCOE(OH) in the presence of Gr2 was carried out only in a mixed solvent, CHCl 3 (10%)/MeOH.…”